Electrical connector device having improved grounding means for shell



Oct. 2, l969 E. R. CARLSON ETAL 3,474,377

ELECTRICAL CONNECTOR DEVICE HAVING IMPROVED GROUNDING MEANS FOR SHELLFiled NOV. 5o, 196e 3,474,377 ELECTRICAL CONNECTOR DEVICE HAVINGIMPROVED GROUNDING MEANS FOR SHELL Ernest R. Carlson, Fairfield, andVincent F. Lipinski,

Stratford, Conn., assignors to Harvey Hubbell,

incorporated, Bridgeport, Conn., a corporation of Connecticut Filed Nov.30, 1966, Ser. No. 597,929 Int. Cl. H011' 3/06, .T3/58, 15/06 U.S. Cl.339-14 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to anelectrical connector device having improved grounding means, and moreparticularly to an electrical connector device having a metallicprotective shell and improved grounding means therefor, includingimproved means to secure a grounding wire directly to the shell.

To satisfy rigorous safety requirements, it is often necessary to groundthe usual exposed metal shells of electrical yconnector devices.Grounding of the metal shells is achieved either by connecting the outermetal shells of the connector body and cap directly in a separate groundcircuit, thereby completing the ground circuit through the shells, or byproviding a grounding shunt or path through the metal shells extendingfrom and being parallel to the usual internal equipment ground circuitof the electrical connectors, which passes through the usual groundcontacts and terminals thereof.

A known arrangement for grounding the exposed metal shells by connectingthem directly in a separate ground circuit comprises securing the groundwires to a ground wire binding screw anchored directly in the metalshell. This arrangement is limited to utilization with relatively smallgrounding wires. A Well known prior art shell grounding shunt includessecuring one end of a flexible metal conductor strip to an internalground wire terminal, as by riveting or welding thereto, and forming theother end so that it is biased into rubbing contact with the interior ofthe shell. It will be readily understood by those skilled in the artthat this shunt construction requires current iiow to pass through atleast two joints, one riveted or welded and the other one of rubbingcontact. One known prior art shunting arrangement eliminates one jointby capturing one end of a flexible metal conductor strip in a clamp typeequipment ground terminal while maintaining the other end biased inrubbing contact with the interior of the shell in the usual manner. Inthis arrangement, the ground wire is placed in direct contact with theground shunt conductor strip and current flow must only pass through onejoint, namely, the rubbing contact joint at the interior of the metalshell.

The grounding means of each of the above arrangements is objectionablebecause heating occurs Wherever the current iiow encounters resistance,for example, in the vicinity of the riveted joints and the rubbingcontact joints. This objectionable heat rise occurs particularly underfull load conditions. Furthermore, it has been found in practice thatthis localized heat build-up causes the riveted joints eventually toloosen and the springnited States Patent loaded shunt conductor strip ofthe rubbing contact joint to lose contact pressure or continuity due tocorrosion. Thus, it is readily apparent that a minimum of joints in thegrounding path is desirable.

Accordingly, it is the primary object of this invention to provide animproved electrical connector device having an improved shell groundingmeans that eliminates a ground terminal within the usual molded terminalsection of the electrical connector device, and a rubbing shunt jointfor grounding the metal shell by providing means for securing arelatively large ground wire directly to the metal shell.

A further object of the invention is to provide an improved shellgrounding means in an electrical connector which minimizes the heat riseand voltage drop in the shell grounding circuit by eliminating allunnecessary joints and all spring biased joints in the grounding path byproviding a ground wire of maximum size secured directly to the metalshell.

A still further object of the invention is to provide an improvedgrounding means for an electrical connector device wherein the groundingcircuit elements are spaced from all current carrying elements andhaving a neat appearing ground wire clamp mounted directly on theexterior of the metal shell.

These objects are achieved in one form by providing an electricalconnector device having improved grounding means for grounding the metalshell which comprises: electrical contact-terminal elements mounted onan insulating body member and arranged to receive leads of theconductive wires of an electrical supply cable; a metal shell withinwhich the insulating body member is disposed; and shell grounding meansarranged to clamp the ground wire of the electrical supply cabledirectly to the metal shell. The grounding means includes a clampingmember arranged to be secured to the exterior of the metal shell and aninwardly extending arcuate portion of the shell which cooperates withthe clamping member to clamp the ground wire therebetween.

Other objects and further details of that which we believe to be noveland our invention will be clear from the following description andclaims taken with the accompanying drawing, wherein:

FIG. 1 is a side elevational view of an electrical connector cap andbody in accordance with the present invention with portions broken awayto show the shell grounding means;

FIG. 2 is a sectional view of an electrical connector device takensubstantially on line 2 2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken substantially along line 33 of FIG. 2 showing a grounding wire secured in place by the clamplingmember;

FIG. 4 is a fragmentary end elevational view of the metal shell andclamping member of the FIGS. 1-3 dev1ce;

FIG. 5 is a fragmentary side elevational view showing the clampingmember mounted on the metal shell; and

FIG. 6 is a perspective view of the clamping member constructed inaccordance with the present invention.

With particular reference to FIG. 1 there is illustrated a connectorbody 1 and a connector cap 2, each of which is provided with an outerprotective cover, a protective metal shell and improved shell groundingmeans including an overlapping clamping member 22. The ground circuit iscompleted through a grounding wire of the electrical cables C andthrough the metal shells 10, which are in electrical contact through theusual spring contact strip 11. The shells 10 are surrounded by outerprotective covers P.

The structural elements to be described, which relate to the invention,are identical in their application to both the connector cap and theconnector body and, therefore,

the specification shall hereinafter refer to an electrical connectordevice and the structure described shall apply equally to both types ofelectrical connector device.

With reference to FIGS. 2-6, there is illustrated a fivewire electricalconnector device constructed in accordance with this invention. Thedevice comprises a usual cup-shaped metal shell disposed in an outercupshaped protective cover P, which may be made of a strong durableplastic material, support a cable strain relief clamp S at one end, andcompress a resilient sealing cushion ring R between it and the closedend of the shell 10. A first body portion 12 made of a rigid electricalinsulation material and cup shaped is located within the shell 10, and asecond body portion 14 of similar material is located within the shellbut spaced from the end of the shell by the first body portion 12,through which the lead wires of an electrical supply cable C extend intothe wiring area 15 formed therebetween. The second body portion 14 ismassive and recessed, and carries the usual clamp-type terminals 16which are arranged to receive the electrically conductive power wires 18of the electrical supply cable C. As can be seen in FIG. 3, theillustrated device includes four electrically conductive power wires 18each connected to one of the clamp-type terminals 16, and a separategrounding wire 20 connected directly to a source of ground and to theshell 10 by the overlapping clamping member 22 which is secured to theshell by means of the mounting screws 24.

The metal shell 10 comprises a substantially cylindrical wall 26 whichis open at one end and has a radially inwardly extending flange 28 atits other end which defines a rear wall having a central aperture 29. Acut-out 30 is formed through the flange 28 and the adjacent portion ofthe cylindrical wall 26, and is located centrally of a radially inwardlyoffset wall portion 32. The portion 32 is concentric with thecylindrical wall 26, but has a smaller radius of curvature so as toallow the overlapping clamping member 22 to be seated flush with theouter surface of the cylindrical wall 26. Located centrally of theportion 32 immediately adjacent the cut-out 30 is a sheared radially`inwardly extending arcuate wire clamp portion 34 which is arranged tocoact with the overlapping clamping member 22 to secure a ground wire 20therebetween. Tapped holes 36 are located on each side of the shearedportion 34 and arranged to threadedly receive the mounting screws 24which secure the overlapping clamping member 22 to the shell 10.

The clamping member 22 comprises a formed metal plate including anarcuate main wall 38, having the same radius of curvature as thecylindrical wall portion 26 of the metal shell, and a substantiallynormal wall 40 which acts to close the cut-out portion in the flange 28when the clamping member is secured in place and further acts as asnubbing strain relief for the ground wire 20. Extending laterallyoutwardly from and described on the same arc as the main wall 38 areopposed lateral mounting arms 42 having screw receiving ways 44. Ways 44are slightly larger than the diameter of the shanks of the mountingscrews 24 and enable the overlapping clamping member 22 to rest on theshanks of the mounting screws 24 and to be firmly clamped in place bythe force of the screw heads when it is desired to secure the clampingmember 22 to the shell 10. Disposed in the main wall 38 are inwardlyextending indentations 46 which coact with the sheared arcuate cableclamp portion 34 to lockingly secure the ground wire 20 in place againstinadvertent removal when the overlapping clamping member 22 is mountedin place.

The first body portion 12 is constructed so that it can be readilyaccepted in the metal shell 10. This Iis accomplished by molding aninwardly offset walled seat 48 arranged to receive the offset portion 32of the metal shell. A cut-out 50 similar to the cut-out 30 in shell 10,is located in the seat 48, and allows the ground wire 2.0 to bepositioned in place. When positioned in the shell 10, the first bodyportion is disposed, as shown in FIG. 2, to have the seat 48 inwardlysurround clamp portion 34 of the shell 10.

To assemble and Wire the connector body 1, the electrically conductivewires 18 are connected to the clamptype terminals 16 in the usualmanner, and the body portions 12 and 14 are secured in the metal shell10. The ground wire 20, is isolated from the conductive wires 18 andmoved from the wiring area 1S through the cut-outs 50 and 30, and ispositioned adjacent the exterior surface of the sheared arcuate cableclamp portion 34. Once the ground wire 20 is so positioned, theoverlapping clamping member 22 is slid axially relative to shell 10 andrested upon the shanks of the mounting scerws 24. Finally, the screwsare tightened and the overlapping clamping member 22 is urged toward theshell 10, thereby securely clamping the ground wire 20 in place betweenthe portion 34 and member 22, and insuring that the wire 20 will not beinadvertently displaced, by driving the inwardly extending indentations46 into the wire to effect a lock.

The connector cap 2 is wired and assembled in a generally similarmanner. The grounding path is continued from the connector body 1 to theconnector cap 2 by means of the usual spring contact strip 11, locatedin the usual outwardly deformed skirt portion 52 of the metal shell ofthe connector body which is biased against the outer surface of theshell of the connector cap.

Having described the improved grounding means for connector deviceshells, it will be readily appreciated by those skilled in the art thatthe secure clamping of the grounding wire 20 affords a highly desirabledirect grounding of the metal shell by a separate ground path, with allits attendant advantages. Further, the ground wire clamping means formedby shell clamp portion 34 and the arcuate wall 38 is configured toaccommodate a variety of large diameter ground wires. Thus, it isapparent that not only has the prior existing deficiency of groundingthe metal shells by means of spring biased grounding shunts beeneliminated, but that the improved grounding means does not require anygrounding terminals, and thereby frees one of the clamp-type terminals16, previously used as a ground wire terminal, for use by anotherelectrically conductive power wire 18. In the improved grounding means,the equipment ground path includes the shell grounding path.

It should be understood that the present disclosure has been made onlyby way of example and that numerous changes in details of constructionand the combination and arrangement of parts may be resorted to withoutdeparting from the true spirit and the scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electrical connector device having improved grounding meanscomprising: a metal shell including a substantially cylindrical wall,and a normal end wall at one end thereof having a central aperturetherein; an insulator body member disposed within said metal shell;electrical contact elements having electrical terminal means carried bysaid body member; said terminal means arranged to secure a plurality ofcurrent-carrying wires; and clamping means including a clamping membersecured to and arranged to clamp a ground wire directly to said metalshell; wherein said clamping member is substantially L-shaped forengagement with the exterior of said metal shell including a main wallportion of said clamping member for lying adjacent said cylindrical wallfor clamping the ground wire between said main wall and said cylindricalwall, and a wall portion disposed substantially normal to said main wallfor acting as a strain reliever for the ground wire.

2. The improved electrical connector device defined in claim 1 whereinsaid main wall is arcuate and has a curvature substantially conformingto the curvature of said cylindrical metal shell for lying adjacentthereto.

3. The improved electrical connector device defined in claim 2 whereinsaid clamping member includes inwardly extending indentations disposedin said main wall portion for lockingly securing the ground wire inplace between said cylindrical wall and said clamping member.

4. The improved electrical connector device defined in claim 2 wherein:said clamping member further includes laterally oppositely extendingarms projecting from said main wall portion which conform to thecurvature of said main wall portion; and said clamping means furtherincludes mounting means cooperating with said arms for securing saidclamping member to said metal shell.

5. An electrical connector device having improved grounding meanscomprising: a metal shell including a substantially cylindrical wall,and a normal end wall at one end thereof having a central aperturetherein; an insulator body member disposed within said metal shell;electrical contact elements having electrical terminal means carried bysaid body member; said terminal means arranged to secure a plurality ofcurrent-carrying wires; and clamping means including a clamping membersecured to and arranged to clamp a ground wire directly to said metalshell; wherein said metal shell includes an offset portion defining awall portion of smaller concentric curvature relative to saidcylindrical wall wherein said clamping member may be seated and,further, includes a radially inwardly extending arcuate portion disposedwithin said offset wall portion arranged to accommodate the ground wire,so that the ground wire may be clamped between said arcuate portion andsaid clamping member.

6. The improved electrical connector device defined in claim 5 wherein acut-out portion is provided in said offset wall portion of said metalshell, adjacent said arcuate portion, and further extends into saidnormal end wall from said offset wall portion to said central aperture,for allowing the ground wire to be disposed between said arcuate portionand said clamping member.

7. The improved electrical connector device defined in claim 6 whereinan insulating spacer is provided with a cut-out, and an offset seatarranged to receive said offset portion of said metal shell, saidcut-out being disposed adjacent said cut-out in said shell when theparts are assembled.

8. An electrical connector device having improved grounding meanscomprising: a metal shell including a substantially cylindrical wall,and a normal end wall at one end thereof having a central aperturetherein; an

insulator body member disposed within said metal shell; electricalcontact elements having electrical terminal means carried by said bodymember; said terminal means arranged to secure a plurality ofcurrent-carrying wires; and clamping means including a clamping membersecured to and arranged to clamp a ground wire directly to said ,metalshell; wherein: said metal shell is provided with an inwardly offsetwall portion defining a smaller concentric curvature than that of saidcylindrical wall, an inwardly extending arcuate portion is disposedwithin said offset wall portion, and a cut-out is located adjacent saidarcuate portion and further extends into said normal end wall from saidoffset wall portion to said central aperture; said clamping meanscomprises a substantially L-shaped clamping member including an arcuatemain wall portion having .a curvature substantially conforming to thecurvature of said cylindrical wall for being seated adjacent saidinwardly offset wall portion and being substantially flush with theouter diameter of said cylindrical wall, laterally oppositely extendingarms projecting from said main wall portion which conform to thecurvature of said main wall portion, inwardly extending indentationsdisposed in said main wall portion for lockingly securing the groundwire in place between said inwardly extending arcuate portion .and saidarcuate main wall portion, and a substantially normal wall portion atone end of said arcuate main wall portion acting as a snubbing strainrelief for the ground wire; and said clamping means further includesmounting means cooperating with said arms for securing said clampingmember to said metal shell.

References Cited UNITED STATES PATENTS 2,032,501 3/1936 Reynolds 339-142,410,618 11/1946 ZelOv 339-14 3,122,604 2/1964 COOk et al 174-51FOREIGN PATENTS 207,092 11/ 1923 Great Britain. 611,474 10/ 1948 GreatBritain.

MARVIN A. CHAMPION, Primary Examiner P. A. CLIFFORD, Assistant ExaminerU.S. Cl. X.R. 339-

